I went from the stock 245/70 R16s to 265/75 R16 Dueler ATs for the first 58,000 in my stock geared & 3" lifted '02 RS. Didn't notice that much of a difference except for a slight drop in fuel mileage and speedo differences. I just went up to some Nitto 285/75 R16 ATs w/ Flowmaster muffler, and my mileage fell even lower PLUS it felt like the torque just disappeared...(too much exhaust flow & even bigger tires don't mix). I got a used PowerVault in great condition and I got some oomph back, but the speedo is still off. I get right at 205 to 210 miles per tank in the city (smaller '02 Rodeo Sport gas tank...grrr!!). More ground clearance with the tires however, plus they look nice...

You can't do wrong w/ 32" (maybe even 33") tires, in my opinion. If you are a heavy duty off-roader, stay between 31" & 32". Hope this helps. Good luck and CHECK YOUR AIR PRESSURE!!